Many applications require that a material be anchored in or to concrete or masonry. For example, anchor bolts are employed in various fields of engineering and construction as strengthening or reinforcing members in rock formations, or in concrete or masonry structural bodies. The bolts, which are typically metallic, are inserted into holes in the rock formations, or concrete or masonry structural bodies, and are fixed or anchored therein by means of an anchor composition. Objects that have been attached to concrete or masonry using anchor bolts include, but are not limited to, electrical conduits, panels, piping and wall sections. Adhesive anchors are preferred over mechanical anchors for anchoring in soft concrete or masonry because, among other reasons, adhesive anchors place less stress on the concrete or masonry. As used herein, the term “masonry” shall include, but is not limited to, stone, brick, ceramic tile, cement tile, hollow concrete block and solid concrete block.
It has been known to use curable synthetic resins as the primary adhesive for the safe fastening of anchoring rods, bolts and similar devices in solid rock, masonry, concrete and the like. Typically, but not exclusively, certain of the starting components of the adhesive composition are kept separate from one another and then combined at or near the point of fastening. In such so called two part systems, the components which are kept separate until the time of use are combined at the site and then introduced to the anchor bolt, the bore or hole prepared to receive the bolt, or both. Thus, the formation of the cured adhesive body that binds the fastener to the base structure is initiated at about the time the fastener is placed in its final position.
Many of the curable adhesive compositions currently used in the industry, and in particular the field of anchoring in or to concrete, rock, and like materials, are based on compounds that are polymerized or cured by addition polymerization of monomers, oligomers, prepolymers and like compounds that have at least one ethylenic unsaturation in the molecule and thus undergo vinyl addition polymerization curing. For example, many acrylic and epoxy-based adhesive compositions are cured by this mechanism in this fashion.
Although the curable adhesive compositions, which have heretofore been used as anchor compositions, have performed with a certain degree of success, applicants have come to appreciate that dramatic and unexpected improvement in performance is not only desirable but also possible.